The regeneration of digital signals requires the ability to distinguish between signal levels. Such ability is often provided by slicing circuitry within the receiver which quantizes the digital signal with respect to a decision level disposed between the signal levels. In prior art transmission systems, e.g., the T1 transmission system described in an article entitled "The D3 Channel Bank", Bell Laboratories Record, Vol. 50, No. 7, April 1972, pg. 229-233, factors such as noise, variations in temperature and/or voltage produce variations in the received signal levels. Such variations can cause errors in signal level detection. Compensation for these signal level changes, therefore, is required for minimizing quantization errors.